In medical practice, it is known that interface pressures constitute the main factor in the development of complications, in particular bedsores, which are a consequence of an individual at risk being kept still for a prolonged period.
More generally, interface pressures also represent an essential element in the concept of comfort.
In the prior art, support apparatus has already been proposed that comprises a support device proper for supporting an element to be supported, in particular the body of a patient, where such a support device is generally known mainly as a "mattress". Naturally, other support devices may be constituted by chairs, cushions, and seatbacks.
Such support apparatus has been described, for example, in Document EP-A-0 218 301=U.S. Pat. No. 4,873,737 or in the Applicant's prior document EP-A-0 676 158. In that prior document, the support device proper comprises at least one closed or controlled-release chamber that is flexible and inflatable to a pressure that is a function of the maximum permitted penetration distance to which the element to be supported is allowed to penetrate into the support. As a result, filling and emptying means are provided for filling or inflating said chamber so as to bring the penetration to less than the maximum permitted penetration distance.
In Document EP-A-0 218 301, it is proposed to modify the pressure when the maximum penetration depth is reached, so that penetration varies as a function of patient weight.
In the Applicant's more recent document EP-A-0 676 158, it is proposed to cause the patient to penetrate to an essentially constant depth into the support device, such as a mattress, independently of the weight of the patient, so as to allow the element to be supported, such as the body of a patient, to penetrate deeply into the support device so as to obtain better weight distribution over the area of the support, by means of a solution that uses a sensor disposed on the support device, such as a mattress, the principle of the sensor being based on the variation of the self-induction coefficient of a coil which is an integral part of an oscillator.